This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The condensin complex functions both during mitosis, to form condensed mitotic chromosomes, and during interphase, to regulate expression of genes. Both of these goals are thought to be accomplished by altering the higher order of structure of chromosomes. In the nematode, C. elegans, two distinct condensin complexes perform these two functions. The mitotic condensin complex plays a role in chromosome segregation, while the dosage compensation complex regulates expression of genes on hermaphrodite X chromosomes to equalize X-linked gene dosage between the sexes. Our long-term goal is to decipher the molecular mechanism of worm dosage compensation and to determine how it relates to the mechanism of chromosome condensation. Biochemical purification of the dosage compensation complex led to the discovery of CAPG-1, a new dosage compensation complex subunit, which also functions in chromosome segregation. To reveal mechanistic similarities between dosage compensation and chromosome segregation, we will use genetic, biochemical, and microscopic tools to analyze the ways in which CAPG-1 can function during both processes.